<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>函数定义</title>

</head>

<body>
<input type="button" value="计算数的平方" id="btn"/>
<script type="text/javascript" language="javascript">
document.getElementById("btn").onclick=function(){
	alert("5的平方是："+5*5);
}
</script>
</body>
</html>
